Base stations managed by wireless service providers transmit radio-frequency (RF) signals to support wireless communication sessions of their subscribing mobile devices. These transmitted signals may cause interference to nearby non-commercial (e.g. public safety) radio equipment that operates in the same or adjacent spectrum allocations. The interference can be intolerable if the non-commercial equipment is part of public safety or critical infrastructure systems; such systems are operated to provide emergency communications and, as such, generally cannot tolerate interference. The interference generally takes two forms: out-of-band emissions (OOBE) from the base station transmitter itself, and intermodulation (IM) products formed in the first stages of the public-safety or other non-commercial receiver from the relatively-strong signals generated by the wireless base station transmitter.
Wireless service providers are obligated to correct interference to public safety and other non-commercial systems that is caused by their base stations and other equipment. Correction of OOBE-related interference can only be done by adding filtering at the wireless service provider's base station itself. Such filtering is readily obtained, assuming the wireless provider's spectrum allocation is contiguous (as is usually the case). Correction of IM-related interference, on the other hand, can only be done through changing the base station transmitter frequencies of operation. Such retuning is practical for systems using a site-by-site channelization plan such as the Integrated Digital Enhanced Network (iDEN). However, current modern wideband technologies, such as the Worldwide Interoperability for Microwave Access (WiMAX) wireless service, do not allow for site-by-site retuning plans. In fact, there currently does not exist a method for manipulating WiMAX signals in order to eliminate interference upon third-party receivers caused by the WiMAX signals.